Joel Benenson will conduct research for the Chan Zuckerberg Initiative, the foundation that the couple set up for their philanthropic projects. The two have vowed to give away virtually all of their fortune through the initiative.
Benenson is a former Democratic pollster who advised both Clinton and President Barack Obama. He's the latest in a string of hires from the political world, including David Plouffe, who ran Obama's campaign in 2008.
The move fuels speculation that Zuckerberg is aiming to get into politics, even though he has said he has no interest.
Facebook wasn't immediately available to comment.